Sensory Systems Flashcards
How are sensory stimuli received and processed by the body?
- sensory organs detect a physical or chemical stimulus in the environment
- specialized sensory cells detect these signals and code them as information to transmit and process thru the nervous system
What is sensory transduction?
the conversion of physical or chemical stimuli into nerve impulses
What are mechanoreceptors?
sensory receptors that respond to physical deformations of their membrane
touch, stretch, pressure, motion, sound
What are hair cells?
specialized mechanoreceptor that senses movement and mechanical vibrations
How do hair cells work?
- hair cells sense vibrations
- vibrations move stereocilia
- motion of stereocilia causes depolarization of the cell
- neurotransmitters are released
How do sound waves travel through the ear?
- sound waves travel into the outer ear
- travels thru ear canal and hits the eardrum, causing it to vibrate
- the vibration moves the ossicles, which transmit vibration to the oval window in the cochlea
What occurs in the basal membrane after the oval window is depressed by the ossicles?
- oval window creates waves that travel thru the cochlear fluid
- waves cause the basilar membrane to move
- movement of basilar membrane is transmitted into electrical impulses within the Organ of Corti
What happens to the hair cells when the basilar membrane moves?
- stereocilia on top of hair cells move against the tectorial membrane
- stereocilia bent toward the kinocilium stimulates the opening of K+ channels at the hair cell terminal, leading to depolarization
When the stereocilia are ____, the hair cell is at rest.
straight
When the stereocilia are bent ____ the kinocilium, the hair cell depolarizes, causing ____.
toward the kinocilium; stimulation
When the stereocilia are bent ____ the kinocilium, the hair cell hyperpolarizes, causing ____.
away from; inhibition
Hair cells at the base of the cochlea transmit ____ frequencies.
high
Hair cells at the apex of the cochlea transmit ____ frequencies.
low
What is the process of auditory transduction at the synapse of the hair cell and auditory nerve?
- K+ ions flow out of stereocilia and into hair cell, causing depolarization
- Depolarization stimulates the opening of Ca+ channels at the terminal
- Excitatory neurotransmitters are released into the synaptic cleft
- Neurotransmitters bind to ligand-gated ion channels of the afferent auditory nerve
- EPSPs are received by the afferent auditory nerve as graded potentials, which fire as action potentials to the brain when threshold is reached
- Signal is received by the brain and processed as sound
What are electromagnetic receptors?
Sensory cells that respond to electrical, magnetic, and light stimuli